CVE-2026-72381
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk11th percentile - higher than 11% of all known CVEs
Summary
A use-after-free vulnerability was found in the Linux kernel's ksmbd (SMB server) module. The issue is a race between reading fp->owner.name during durable handle owner comparison and freeing it in the reopen path. An attacker could exploit this to gain unauthorized access or cause a system crash.
Risk Assessment
The vulnerability may lead to kernel memory corruption, potentially enabling privilege escalation or denial of service. Organizations using ksmbd (SMB) are exposed to attacks from the local network.
Recommendation
Immediately update the Linux kernel to a version containing the fix (commit 7ce4fc40018d and serialization with fp->f_lock). If updating is not possible, consider disabling the ksmbd module or restricting access to the SMB service.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free of fp->owner.name in durable handle owner check Two concurrent SMB2 durable reconnects (DH2C/DHnC) on the same persistent_id race the fp->owner.name compare-read in ksmbd_vfs_compare_durable_owner() against the kfree() in ksmbd_reopen_durable_fd()'s reopen-success path. fp->owner.name is a standalone kstrdup() buffer whose lifetime is independent of the fp refcount, and the two sites share no lock: the compare reads the buffer while the reopen frees it, so the strcmp() can dereference freed memory. Commit 7ce4fc40018d ("ksmbd: fix durable reconnect double-bind race in ksmbd_reopen_durable_fd") made the fp->conn claim atomic under global_ft.lock (closing the owner.name double-free and the ksmbd_file write-UAF), but the compare-read versus reopen-free pair was left unserialized. BUG: KASAN: slab-use-after-free in strcmp+0x2c/0x80 Read of size 1 by task kworker strcmp ksmbd_vfs_compare_durable_owner smb2_check_durable_oplock smb2_open Freed by task kworker: kfree ksmbd_reopen_durable_fd smb2_open Allocated by task kworker: kstrdup session_fd_check smb2_session_logoff The buggy address belongs to the cache kmalloc-8 Serialize both sides of the race with fp->f_lock. The global durable file-table lock still protects the durable reconnect claim, but fp->owner.name is per-open state and does not need to block unrelated durable table lookups or reconnects. The teardown is left at its existing location after the reopen-success point so that an __open_id() rollback still retains owner.name for a later legitimate reconnect to verify.